[petsc-users] -pc_fieldsplit_schur_precondition

[Matthew Knepley]

On Wed, Dec 4, 2019 at 8:20 AM Cotter, Colin J <colin.cotter at imperial.ac.uk>
wrote:

> Dear PETSc users,
>   I'm curious: how does PETSc compute the Schur complement matrix under
> the option pc_fieldsplit_schur_precondition full? Does it use sparse linear
> algebra?
>

The action of the Schur complement is always MatMult() KSPSolve() MatMult().

The precondition matrix can be formed several different ways:
https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCFieldSplitSetSchurPre.html

  Thanks,

     Matt


> all the best
> --Colin
>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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